For the gaseous reaction,$N_2O_4(g) \to 2NO_2(g)$,which of the following relations is correct?

The heat change for the following reaction at $298 \ K$ and at constant pressure is $+7.3 \ kcal$: $A_2B_{(s)} \to 2A_{(s)} + 1/2B_{2(g)}$,$\Delta H = +7.3 \ kcal$. The heat change at constant volume would be:

For the reaction $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$ at $298 \ K$,the enthalpy change $\Delta H$ is $-92.38 \ kJ$. What is the value of $\Delta U$ in $kJ$ at $298 \ K$?

For which reaction is $\Delta H \neq \Delta U$?

An ideal gas,$\overline{C}_{V} = \frac{5}{2} R$,is expanded adiabatically against a constant pressure of $1 \ atm$ until it doubles in volume. If the initial temperature and pressure are $298 \ K$ and $5 \ atm$,respectively,then the final temperature is . . . . . . $K$ (nearest integer). [$\overline{C}_{V}$ is the molar heat capacity at constant volume]

During the melting of an ice slab at $273 \ K$ and $1 \ atm$ pressure: